Scissortail sergeant
A large damselfish with black stripes and a military-inspired name.
The scissortail sergeant, also called the striptailed damselfish (Abudefduf sexfasciatus), is a sizable member of the Pomacentridae family. Its common name comes from the black stripes on its tail and body, which resemble the chevrons on a military sergeant’s uniform, much like those of the sergeant major damselfish. It typically reaches about 16 centimeters (6.3 inches) in length, though it can grow up to 22 centimeters (8.7 inches). These fish inhabit coral reefs in tropical waters down to depths of 1 to 20 meters, often gathering in groups around a single coral head. Their range spans the Indo-Pacific region, including the Red Sea, with populations in the Indian Ocean (eastern Africa, Madagascar, Seychelles, the Persian Gulf, India, Sri Lanka, the Bay of Bengal, the Andaman Sea, Indonesia, and Australia) and the Pacific Ocean (the Great Barrier Reef, the Gulf of Thailand, Indonesia, the Philippines, Taiwan, Japan, and various Pacific islands as far as Hawaii). A single individual was recorded in the eastern Mediterranean near Athens, Greece, in 2017, likely from an aquarium release. Adults live on coral reefs, while younger fish stay in the open sea, at depths of 1 to 20 meters (3.3 to 65.6 feet). The fish is white with five vertical black bands and two horizontal black bands on the tail lobes. It feeds on algae, zooplankton, and sometimes its own eggs. It is preyed upon by fish from the Labridae and Serranidae families. In the wild, it aggregates in large groups above coral. In the aquarium trade, it is popular but very aggressive, making it difficult to keep with other fish of similar size. For reproduction, females lay eggs in patches on a firm substrate, and males guard them vigorously until they hatch. Males are polygamous, collecting eggs from up to 12 females, who spawn and then leave. Males handle all parental care, which is common in fish because territorial males can guard multiple clutches while attracting new mates. They undergo brood cycling, alternating between a mating phase (where they turn gold and display to attract females, lasting two to three days) and a parental phase (where they lose the gold color and guard eggs for four to five days). Filial cannibalism—eating their own offspring—occurs during the parental phase. Females pool their eggs with others in a single male’s territory to create larger broods.
Quick Facts
- Taxon
- Abudefduf sexfasciatus
Facts from the source article.
Lore & Background
Scissortail sergeants are found on coral reefs in the Indo-Pacific region, including the Red Sea, at depths of 1 to 20 m. They often live in a group surrounding a single head of coral. Adults inhabit coral reefs while younger individuals live in the open sea. The fish is white with five vertical black bands and two horizontal bands on the lobes of its tail. This species feeds on the larvae of invertebrates, zooplankton, smaller fishes, crustaceans, and various species of algae, as well as its own eggs. It is preyed upon by some members of the Labridae and Serranidae families. In the aquarium trade, it is popular but very aggressive and difficult to keep peaceful with other similar-sized fishes.
Reader's Guide
The scissortail sergeant is notable for its distinctive striped appearance and its complex reproductive behavior, particularly the phenomenon of filial cannibalism. The article describes how males alternate between a mating phase, where they turn gold and display to attract females, and a parental phase, where they guard eggs. Females employ strategies such as pooling eggs with other females to create larger broods, which reduces predation risk and decreases the likelihood of male cannibalism. Some females even lay 'test eggs' to assess a male's parental quality before committing a full clutch.
Filial cannibalism is described as an evolutionarily adaptive behavior that balances the loss of foraging opportunities. Males may eat nonviable eggs or entire broods when the cost-to-benefit ratio of parental investment is too high. Smaller broods early in development are more likely to be cannibalized. Sneaking by other males, which reduces a father's relatedness to his brood, also increases cannibalism. Supplementary feeding can decrease cannibalistic tendencies. The species is popular in the aquarium trade, though its aggression poses challenges. A single record from 2017 near Athens, Greece, suggests aquarium release has extended its range.
Did You Know?
- The scissortail sergeant can grow up to 22 centimetres (8.7 in) in maximum length.
- Males undergo brood cycling, alternating between a gold-colored mating phase and a four- to five-day parental phase.
- Females may lay 'test eggs' to confirm a male's parenting ability before committing a full clutch.
- A single record of this species was reported in 2017 in the eastern Mediterranean Sea near Athens, Greece, likely from aquarium release.
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